1. Field of the Invention
The present invention relates to a liquid crystal display device.
2. Description of the Related Art
Differing from self-emitting display devices as represented by CRT (Cathode Ray Tube) and PDP (Plasma Display Panel), liquid crystal display devices are non-emitting display devices that display videos and images by controlling one or both of transmittance of light from a light source and reflectance of ambient light.
The liquid crystal display devices have advantages in that they are thin and light and consume less power. Thus, in recent years, the liquid crystal display devices are widely used as various displays, for example, such as liquid crystal displays of liquid crystal televisions and personal computers, or liquid crystal displays of mobile electronics such as cellular phones.
The liquid crystal display devices have a liquid crystal display panel and a driver circuit that drives the liquid crystal display panel. The liquid crystal display panel is a display panel in which liquid crystal materials are enclosed between a pair of substrates and includes a display region which is configured by a group of numerous pixels. Each pixel has a pixel electrode, a common electrode, and a liquid crystal layer. Alignment of the liquid crystal layer (liquid crystal molecules) is changed by a potential difference between the pixel electrode and the common electrode, whereby one or both of transmittance and reflectance of light is changed. An arrangement mode of the pixel electrode and common electrode is roughly classified into two modes. One mode arranges the pixel electrode and common electrode on different substrates, whereas the other mode arranges them on the same substrate.
A liquid crystal display panel in which the pixel electrode and common electrode are arranged on the same substrate is generally called an IPS (In-Plane Switching) mode liquid crystal display panel. In such a liquid crystal display panel, liquid crystal molecules rotate in an in-plane direction, so that an effective optical axis is rotated within a plane, whereby one or both of transmittance and reflectance of light is controlled. In a liquid crystal display device having the IPS-mode liquid crystal display panel, since the alignment direction of the liquid crystal layer is approximately horizontal, the liquid crystal layer exhibits a small change in retardation with a change in viewing angle. Therefore, it is known that the IPS-mode liquid crystal display device can achieve a wide viewing angle.
An arrangement mode of the pixel electrode and common electrode in the IPS-mode liquid crystal display panel is roughly classified into two modes. One mode arranges the pixel electrode and common electrode on the same surface of an insulating layer so as to face each other, whereas the other mode arranges the pixel electrode and common electrode so that they are stacked onto each other with an insulating layer disposed therebetween. In the mode where the pixel electrode and common electrode are arranged on the same surface of the insulating layer, the pixel electrode and common electrode are formed into an interdigital shape in planar view, and, for example, are arranged in such a way that fingers of the pixel electrode and fingers of the common electrode are alternately arranged. In the mode where the pixel electrode and common electrode are stacked onto each other, electrodes disposed closer to the liquid crystal layer are formed into an interdigital shape in planar view, whereas the other electrodes are formed into a flat plate-like shape in planar view, for example.
As to the specific configuration of pixels of the IPS-mode liquid crystal display panel, various configurations are known. Moreover, as to the driving method of the IPS-mode liquid crystal display device, various methods are known. Therefore, in this specification, illustrations of related art documents relating to the specific configuration and driving method of the known IPS-mode liquid crystal display device will be omitted.